Sterling Point Research, in collaboration with Children's Hospital Boston, is proposing to develop a Risk Assessment Tool for Hemodynamic Monitoring (RAHM) of post-operative infants with congenital heart disease. At its core a physiology observer utilizes multiple measurements to estimate a patient's physiologic state, while computing the uncertainty of the estimation. This information is then translated to a risk profile which informs clinicians of potential complications that may require a change in treatment. Consequently, RAHM will help physicians better understand the tradeoffs between invasive and noninvasive modes of measurement. This system will minimize the use of invasive physiologic measurements, thus reducing morbidity and mortality while concomitantly reducing length of stay in the cardiac intensive care unit (CICU). In the Phase 1 effort, SPR will focus on constructing the observer and verifying its utility through retrospective human studies. In Phase 2, RAHM will be refined using additional patient data, and implemented on Children's Hospital Boston's Cardiac Intensive Care Unit as a stage for preliminary clinical trials.